A new view of territoriality in large eagles: the territory pre-exists regardless of their occupants.

Abstract 1. The knowledge about territoriality and space use by predators is a topic of great interest in the study of animal behavior and conservation biology. Examining the plasticity of territory limits, the topology and how territories can be modified depending on their owners is important to deepen into the behavior of territorial species. 2. Here, we analyzed the variations and tested the similarity of the home-range of individuals from the same territory using the data provided by 51 Bonelli's eagles from 22 different territories, tagged with GPS/GSM dataloggers in eastern Spain. 3. We analyzed the percentage of overlap of the annual home-range considering the 95% kernel density estimator between individuals of the same territory. Also, we analyzed the variation in the home range size according to three different kernel levels (95%, 75% and 50%) and the annual eccentricity of each individual home-range as a complementary metric to study the topology of territories across years. We also analyzed the changes in territory size and topology after the replacement of territory owners either by a single individual or by the entire pair. 4. Our results show that territories, regardless of the occupying members, have the same topology and extension and that their limits hardly vary across time. 5. Therefore, the identification and conservation of territories of large eagles regardless of their owners are key to ensuring species recovery in the long term, which is particularly important for endangered species such as the Bonelli’s eagle. Finally, our study highlights satellite telemetry's importance in further investigating the behavioral ecology and its conservation implications in large eagles.